Food cooking control devices are known the aim of which is to facilitate and standardize food preparation without needing to have specialized labor. These devices consist of elements equipped with cannulas or rods provided with temperature detectors which are inserted into the food to be controlled. The element is usually connected to means for processing the information received from the detectors, such that food cooking is controlled according to certain parameters.
The different devices have a common element, all of them are inserted into the food but lack means for determining the exact position of the device inside the food. Since the exact position of the temperature sensors inside the food is not known, it is not possible for them to control the energy accumulated in the temperature gradient occurring between the outer area of the food through which it receives heat and the center of the food while it is cooked. Nevertheless this energy accumulated in the gradient between the inside and the outside will appear when the cooking ends and the supply of energy maintaining the gradient ceases. The energy accumulated in the gradient will diffuse until equilibrium is reached and the temperature in the entire piece becomes equal.
Additionally, there is another issue which the different devices do not tackle either, during cooking processes, foods change in dimensions during the process, increasing them in some cases and reducing them in others such that the center of the raw food is not the same point as the its center throughout the cooking process.
U.S. Pat. No. 6,753,027 describes a method for controlling the cooking process and a detector for carrying out said method. By means of said method at least two temperature values are obtained by means of a detector adapted to be at least partially stuck into the food to be cooked. Said temperature values are obtained at several points in random positions inside the food at different depths, the separation distances between the detection points being fixed and known, and at least at another point outside the food determining the temperature of the environment.
Based on these values, an extrapolation is done and food core temperature is calculated in combination with the temperature taken outside the food to control the cooking thereof.
The drawback of the described method is that the temperature detector is stuck in a different way inside the food every time it is used, such that the points at which the temperature is measured are different for each use. Although the separation distance between the different detection points is known, it is not possible to know the relative position thereof inside the food. This makes it impossible to position the detection points in the most interesting precise zones to control the food temperature. Thus, if the size of the foods to be controlled is different, the temperature taking points are positioned in a substantially different manner in relation to the thickness of each food, which makes the data obtained useless. This drawback is more obvious in foods which are semi-submersed in liquids, or in foods receiving heat through only one side.
Therefore, the described method does not allow applying uniform cooking parameters giving the same result for all the foods in which it is used, since the temperature values taken for a food correspond to zones different from those controlled in another food.
Patent DE-A-4032949 describes a device proposing the use of two temperature sensors, one for being positioned on the surface of the food and the other one inside such food which can be stuck at greater or lesser depth into the food but without precision or control.
European patent EP 1473554 describes a utensil and a method for controlling a cooking device. This utensil consists of a temperature measurement device with two temperature detectors. One of said detectors is at one end of the utensil in contact with the bottom of a cooking receptacle, and the other device is positioned at a certain distance from said end.
This utensil allows controlling the temperature of the cooking receptacle and of the cooked food. Nevertheless, the described utensil has the drawback that it only allows controlling points positioned at fixed and determined distances from the food. If the size of the different foods changes, or the utensil is placed differently, the detectors of the utensil are positioned at different points or even outside the food. Furthermore, it must be added that most foods change in shape and/or geometry during the cooking process, which makes their use be limited to controlling the cooking of regular liquids or foods with constant thickness and which do not change in geometry during the cooking process.
Furthermore, the temperature detector in contact with the bottom of the receptacle may not be very useful, since the heat supplied to the food is transmitted in a different manner according to the characteristics of the food to be controlled and the heat source.
In the case of griddles, which can have different shapes (flat, grooved) and supply heat by means of different sources (charcoal, infrared, air), the information provided by this contact detector is not relevant. This is due to the fact that the amount of heat absorbed by the food is different from the amount of heat absorbed by the detector. Heat acts in a different manner on the food according to the characteristics of the source and the food itself.
U.S. Pat. No. 4,441,693 relates to a method for controlling the cooking process of a food in an oven comprising the steps of determining the power absorbed in said food during cooking, and determining the average food temperature using the absorbed power derivative and cooking parameters according to the equation:Ta=To+a1[(Pa)t/M]+a2[(Pa)t/M]2+a3[(Pa)t/M]3 where,Ta is the average food temperature,To is the initial food temperature,Pa is the power absorbed in the food,t is the food cooking time,M is the initial food mass, anda1, a2, a3 are coefficients relating to the food weight loss and are experimentally determined for several food categories and amounts.
In addition, patent EP 1688721B1 describes a method for determining the turn-over time of a food. Said method only refers to the first turn-over of the food and calculates the time in which it is carried out according to the different between the final temperature and the initial temperature of the food.
Patent EP-B1-1688721 describes a method and a device for determining the turn-over time of a product to be cooked, with a series of steps in which an initial food temperature and another final temperature are started from and temperatures inside the food are gradually acquired with a member which can be inserted in the food provided with a probe, such as the one described above and with the same deficiencies. According to this method, the food is turned over when the temperature in the probe reaches a fraction of the desired total temperature. The method has the drawback of the imprecision of the temperature taking zone and of ignoring the thermal inertia, or heat gradient explained.
Patent DE-A-19609116 describes a food cooking method, particularly for cooking large pieces of meat, which states that the core temperature is measured several times successively during the cooking. However, this document does not teach how to position a temperature probe in a precise manner inside the food.